<html><body><div class="content"><div class="section" id="the-type-statement">
<span id="type"></span><h2>The <a class="reference internal" href="#type"><tt class="xref std std-keyword docutils literal"><span class="pre">type</span></tt></a> statement</h2>
<pre id="index-47">
<strong id="grammar-token-python-grammar-type_stmt"><span id="grammar-token-type-stmt"></span>type_stmt</strong> ::=  'type' <a class="reference internal" href="lexical_analysis.html#grammar-token-python-grammar-identifier"><code class="xref docutils literal notranslate"><span class="pre">identifier</span></code></a> [<a class="reference internal" href="compound_stmts.html#grammar-token-python-grammar-type_params"><code class="xref docutils literal notranslate"><span class="pre">type_params</span></code></a>] &quot;=&quot; <a class="reference internal" href="expressions.html#grammar-token-python-grammar-expression"><code class="xref docutils literal notranslate"><span class="pre">expression</span></code></a>
</pre>
<p>The <code class="xref std std-keyword docutils literal notranslate"><span class="pre">type</span></code> statement declares a type alias, which is an instance
of <a class="reference internal" href="../library/typing.html#typing.TypeAliasType" title="typing.TypeAliasType"><code class="xref py py-class docutils literal notranslate"><span class="pre">typing.TypeAliasType</span></code></a>.</p>
<p>For example, the following statement creates a type alias:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="nb">type</span> <span class="n">Point</span> <span class="o">=</span> <span class="nb">tuple</span><span class="p">[</span><span class="nb">float</span><span class="p">,</span> <span class="nb">float</span><span class="p">]</span>
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<p>This code is roughly equivalent to:</p>
<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">annotation</span><span class="o">-</span><span class="k">def</span> <span class="nf">VALUE_OF_Point</span><span class="p">():</span>
    <span class="k">return</span> <span class="nb">tuple</span><span class="p">[</span><span class="nb">float</span><span class="p">,</span> <span class="nb">float</span><span class="p">]</span>
<span class="n">Point</span> <span class="o">=</span> <span class="n">typing</span><span class="o">.</span><span class="n">TypeAliasType</span><span class="p">(</span><span class="s2">&quot;Point&quot;</span><span class="p">,</span> <span class="n">VALUE_OF_Point</span><span class="p">())</span>
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<p><code class="docutils literal notranslate"><span class="pre">annotation-def</span></code> indicates an <a class="reference internal" href="executionmodel.html#annotation-scopes"><span class="std std-ref">annotation scope</span></a>, which behaves
mostly like a function, but with several small differences.</p>
<p>The value of the
type alias is evaluated in the annotation scope. It is not evaluated when the
type alias is created, but only when the value is accessed through the type alias’s
<code class="xref py py-attr docutils literal notranslate"><span class="pre">__value__</span></code> attribute (see <a class="reference internal" href="executionmodel.html#lazy-evaluation"><span class="std std-ref">Lazy evaluation</span></a>).
This allows the type alias to refer to names that are not yet defined.</p>
<p>Type aliases may be made generic by adding a <a class="reference internal" href="compound_stmts.html#type-params"><span class="std std-ref">type parameter list</span></a>
after the name. See <a class="reference internal" href="compound_stmts.html#generic-type-aliases"><span class="std std-ref">Generic type aliases</span></a> for more.</p>
<p><code class="xref std std-keyword docutils literal notranslate"><span class="pre">type</span></code> is a <a class="reference internal" href="lexical_analysis.html#soft-keywords"><span class="std std-ref">soft keyword</span></a>.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.12.</span></p>
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<div class="admonition seealso">
<p class="admonition-title">See also</p>
<dl class="simple">
<dt><span class="target" id="index-48"></span><a class="pep reference external" href="https://peps.python.org/pep-0695/"><strong>PEP 695</strong></a> - Type Parameter Syntax</dt><dd><p>Introduced the <code class="xref std std-keyword docutils literal notranslate"><span class="pre">type</span></code> statement and syntax for
generic classes and functions.</p>
</dd>
</dl>
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